Whether it is removing Poa annua from cool-season turf or organic matter from warm-season grass, fraise mowing has been an accepted practice for renovating athletic fields for nearly a decade. Although it is an invasive practice, fraise mowing and other ultra-aggressive grooming practices also have a place in golf, says Jerad Minnick, a sports turf management consultant.
"If you have a problem with organic matter on a golf course, this can fix it," Minnick said during the recent Tennessee Turfgrass Association Conference and Show.
Fraise mowing utilizes hundreds of blades on a helix-shaped rotor that remove material from the surface, leaving behind what Minnick says are stronger, healthier plants that can be ready for traffic in a few days to a few weeks depending on how much is removed.
The process was developed in 1996 by Ko Rodenburg, a Dutch sports field manager, to remove Poa annua from cool-season sports turf. True fraise mowing is performed with the Imants Koro Field Topmaker that was named for Rodenburg. But similar aggressive grooming practices can be achieved with equipment from other manufacturers. Fraise mowing often results in phrases such as "whoops" or "uh oh" when sports turf managers, superintendents or facility managers and administrators see just how much organic matter it displaces.
The material removed and how much depends on two factors: whether the surface is warm- or cool-season and the depth setting of the machine taking it out. A Kentucky bluegrass or ryegrass soccer field can produce 12 22-yard dumpsters of organic material, and a Bermudagrass field will yield twice as much, Minnick says.
The results, Minnick says, are worth it, and its practice is used increasingly in sports turf management in the U.S. and abroad with all professional soccer fields in the United Kingdom employing it since its inception. It also is used in the U.S. on everything from high school and municipal fields to professional soccer stadiums.
Whether it was during his days managing the Maryland Soccerplex near Washington, D.C., or consulting on field renovation projects throughout the United States and Europe, Minnick says fields can be ready for play within four weeks or so of fraise mowing, even under adverse conditions.
Two weeks of record cold temperatures descended on north-central Texas immediately after a fraise mowing procedure to renovate the Bermudagrass playing surface at Toyota Stadium, home to the FC Dallas MLS franchise. With the use of tarps to protect the surface from freezing temperatures, the fields were ready for play four weeks after a mowing procedure that Minnick and others describe as verticutting on steroids.
He oversaw a similar procedure in Paris in which fraise mowing was incorporated to remove Poa annua from a ryegrass field six weeks before the start of the season.
John Jeffreys, superintendent at Pinehurst No. 2, has used Turfplaning Services, which employs a similar procedure to renovate par 3 tees that had become elevated over time and on greens surrounds to manage what he called a "collar dam" on the famed Donald Ross design.
"It had become like a bowling lane bumper around the green," Jeffreys said. "We had to peel that out and eliminate that elevated collar."
Removal of organic material improved how water moved off the greens after rain events, said Jeffreys who also performs what he called very aggressive verticutting with a pair of Wiedenmann units. Collars also were more firm and the turf healthier after being exposed to such an aggressive practice. The work was performed when the course already was closed for renovation work, so taking areas out of play for weeks at a time was not an issue.
"The best aerification you can do on Bermudagrass is to get rid of that organic matter," he said. "It really slows water from exiting the green."
Minnick said such practices are catching on in Florida. Many of the courses there are opting for closing nine holes for a few weeks through the middle of summer and completing the other nine the following year.
Mark Langner, CGCS, formerly of FarmLinks in Alabama and currently of Aqua Aid, which represents Campey Turfcare Systems and Imants, also at the Tennessee show, said courses in other parts of the Southeast, including high-profile facilities in the Birmingham area.
"Because of how it controls thatch, you can get on the fairways right after it rains because that sponge that holds the water is gone," he said. "It might cost a little revenue up front for courses to close, but they'll capitalize on the backside because the conditions are so much better."